Relations between the bone density values from computerized tomography, and implant stability parameters: a clinical study of 230 regular platform implants

Aims: The objective of this study was to determine the relationship between bone density, insertion torque, and implant stability at implant placement. Materials and Methods: One‐hundred and eight patients were treated with 230 Brånemark System implants. A computerized tomography (CT) machine was used for pre‐operative evaluation of the jaw bone for each patient. The maximum insertion torque values were recorded with the OsseoCare equipment. Implant stability measurements were performed with the Osstell machine for only 142 implants. Results: The mean bone density and insertion torque values were 721±254 Hounsfield unit (HU) and 39.1±7 N cm for 230 implants, and the correlation was significant (r=0.664, p<0.001). The mean bone density, insertion torque, and resonance frequency analysis values were 751±257 HU, 39.4±7 Nc m, and 70.5±7 implant stability quotient (ISQ), respectively, for 142 implants. Statistically significant correlations were found between bone density and insertion torque values (p<0.001); bone density and ISQ values (p<0.001); and insertion torque and ISQ values (p<0.001). Conclusion: The bone density values from pre‐operative CT examination may provide an objective assessment of bone quality, and significant correlations between bone density and implant stability parameters may help clinicians to predict primary stability before implant insertion.     

A comparison between insertion torque and resonance frequency in the assessment of torque capacity and primary stability of Brånemark system implants

summary The aim of this study was to determine primary stability and insertion torque of Brånemark System implants placed in the anterior mandible, and to evaluate a possible correlation between primary stability and insertion torque. Thirty edentulous patients were treated with 60 Brånemark System implants using a one‐stage technique. The insertion torque values of all implants were recorded with the Osseocare equipment. Immediately after implant placement, each implant was connected to the transducer of an Osstell machine to measure the primary implant stability. The average insertion torque and resonance frequency values were 41·5 ± 5·8 and 74·1 ± 3·8 for 30 implants. The correlation between insertion torque and resonance frequency values indicated a statistical significance (P < 0·001). The difference between mean insertion torque values for female and male patients was statistically significant (P < 0·001). No significant difference (P > 0·05) was found between younger and older patients with mean insertion torque values of 43·1 ± 4·7 and 40·1 ± 6·5 respectively. The results of this study showed a strong correlation between the primary stability and insertion torque values of Brånemark System TiUnite MKIII implants at the time of implant placement.     

Astra Tech and Brånemark System implants: a prospective 5-year comparative study. Results after one year

Background: Endosseous dental implants are used frequently, and many implant systems are available. The scientific documentation of the implant system presents a great variation, and it is often difficult to compare studies of different systems. Purpose: The aim of this study was to compare two Swedish implant systems (Astra Tech and Brånemark System± implants), in a prospective randomized study. Materials and Methods: Sixty-six patients were equally distributed between the two implant systems; 184 Astra Tech and 187 Brånemark System implants were used. The patients have been followed annually with clinical and radiographic examinations. The results after 1 year are reported. Results: The abutment procedure was found to be easier and less time-consuming with Astra Tech than with Brånemark implants. The operation times in minutes (mean ± SEM) were for the respective implant 35 ± 4.0 and 51 ± 4.8 in the maxilla and 32 ± 3.8 and 43 ± 2.4 in the mandible. The differences in both cases were significant: p <.02 and p <.05, respectively. The failure rate for Astra Tech implants was 0.5% and for Brånemark implants 4.3%. The difference was significant (p <.05); however, taking into account that five of the eight implant losses in the Brånemark implant group occurred in one patient, an intraindividual correlation cannot be excluded. Therefore, this result should be interpreted with caution. The marginal bone level changes were examined already from the fixture installation. The major bone loss was found between fixture installation and baseline. This bone loss was several times greater than the bone loss between the baseline and the 1-year follow-up. The total bone loss during the observation period did not differ significantly between the systems, but they had different resorption patterns. The bone loss in the upper jaw between baseline and 1-year follow-up was 0.22 ± 0.14 and 0.03 ± 0.09 mm for the Astra Tech and Brånemark implants, respectively. In the lower jaw, the loss was -0.31 for both systems. The frequency of plaque accumulation and bleeding on probing did not differ between the implant systems. Conclusions: Abutment connection with Astra Tech implants was simpler than the corresponding surgery with Brånemark System implants and the survival rate of Astra Tech implants was higher than that of Brånemark system implants.     

Marginal bone reaction to oral implants: a prospective comparative study of Astra Tech and Brånemark System implants

Abstract: In earlier studies of Astra Tech and Brånemark System implants, high survival rates and small marginal bone changes have been demonstrated. The aim of this study was to compare the two systems, primarily with regard to marginal bone changes, but also with regard to other clinical variables of interest. The present paper describes the results after three years. Sixty‐six patients were included in the study and randomly assigned to treatment with Astra Tech implants (n=184) or Brånemark System implants (n=187). The marginal bone level was radiographically examined at fixture insertion, at abutment connection, at baseline (delivery of the prosthetic construction) and at 1‐ and 3‐year follow‐up examinations. Between fixture insertion and the baseline examination, the pattern of marginal bone resorption differed between the two systems. However, there was no significant marginal bone change between baseline and the 1‐year examination or between the 1‐ and 3‐year examinations. Nor were there any differences between the systems. The mean bone loss in the upper jaw between BL (baseline) and 3 years was 0.2±0.3 mm for Astra Tech implants and 0.2±0.1 mm for Brånemark System implants. The corresponding figures for the lower jaw were 0.3±0.2 mm and 0.2±0.1 mm. The survival rate of Astra Tech implants was significantly higher (98.9%) than for Brånemark System implants (95.2%). However, five of the nine implant losses in the Brånemark group occurred in one patient. For that reason, this result must be interpreted with caution. The number of patients with implant losses did not differ significantly between the systems. Few complications were recorded up to 3 years.     

Astra Tech and Brånemark system implants: a 5-year prospective study of marginal bone reactions

Abstract: This paper describes the 5‐year results of a comparative study between Astra Tech and Brånemark system implants. The aim was to compare the systems primarily with regard to bone level changes, and also with regard to other variables of interest. Sixty‐six patients with edentulous jaws were included in the study. Randomisation schedules were used to allocate the patients to the two implant systems. 184 Astra Tech implants with a titanium‐blasted surface and 187 Brånemark implants with a turned surface were used. The implants were inserted with a two‐stage technique and the insertion followed the routines for the respective implant system. All patients were provided with full‐arch fixed bridges. All patients were followed up with clinical and radiographic examinations from fixture insertion to the 5‐year follow‐up. The total mean bone level change in the upper jaw between fixture insertion and the 5‐year examination was ?1.74±0.45 mm at the Astra implants and ?1.98±0.21 at the Brånemark implants. The corresponding values for the lower jaw were ?1.06±0.19 for Astra and ?1.38±0.17 for Brånemark. The major postoperative changes of the marginal bone level took place between fixture insertion and baseline. During this period, there was also a different pattern of bone remodelling between the implant systems. Between baseline (prosthesis connection) and the 5‐year examination, the marginal bone level changes were small, with no difference between the implant systems. The implant stability was examined with the supraconstructions removed. At the 5‐year examination, the survival rate for Astra Tech implants was 98.4% and for the Brånemark implants it was 94.6%. The difference was not statistically significant.     

The anchorage of Brånemark and ITI implants of different lengths. I. An experimental study in the canine mandible

Abstract: The anchorage of machined Brånemark and ITI TPS‐coated implants of various lengths was investigated in an animal model. Brånemark fixtures 7 and 10 mm long and ITI implants 6 and 10 mm long were inserted in the mandible of dogs and were reverse‐torqued after 3 months of healing. The failing mode was different for the two implant systems. For the ITI implants, loosening coincided with the peak reverse‐torque values. For the Brånemark fixtures, two reverse‐torque values were identified and recorded, a ‘start to rotate’ and a peak value. The ‘start to rotate’ values for the 7 and 10 mm Brånemark fixtures were 36.67 and 38.57 Ncm, respectively, the peak values were 61.88 and 69.13 Ncm. The increase in implant length from 7 to 10 mm did not significantly improve the anchorage. The mean reverse‐torque values for the 6‐ and 10‐mm ITI implants were 104.66 and 192.25 Ncm, respectively; the difference was statistically significant. The mean removal torque of the 6‐mm ITI implant was higher than the 7‐ and 10‐mm Brånemark implants. It is suggested that the distinct anchorage magnitude and the distinct loosening patterns registered for both implant systems might be related to the various surface states. The latter might account for the different failure tendencies mentioned in the literature for short Brånemark and ITI implants.     

Correlation of insertion torques with bone mineral density from dental quantitative CT in the mandible

Abstract: Objective: The aim of this study was to establish a correlation between bone mineral density measured preoperatively with dental computed tomography (CT), and insertion torque of screw‐shaped dental implants. Material and methods: In eight human mandibles obtained postmortem, bone mineral density (BMD) was measured with dental quantitative CT (DQCT) and correlated with insertion torque values at 45 implant sites during insertion of screw‐shaped dental implants (Brånemark System MKIII, Nobel Biocare, AB, Göteborg, Sweden). Results: A significant correlation (r=0.86, P<0.001) between BMD and torque values was observed, indicating that local BMD at a specific implant position is related to the supportive capacity of the jawbone. BMD exhibited no correlation with bone height or position. Conclusion: The noninvasive assessment of BMD using a DQCT scan employing a low‐dose protocol may be used to estimate expected primary stability depending on BMD, implant type and preparation procedure. These data may therefore help the surgeon to select the optimum implant position, implant type and operation technique.     

Nonsubmerged and submerged implants in the treatment of the partially edentulous maxilla

Background: Dental implants vary in design and surfaces. In addition, different surgical techniques have been used for implant insertion. The ITI Dental Implant System (Straumann AG, Waldenburg, Switzerland) has always required a one‐stage technique, whereas the Brånemark System (Nobel Biocare AB, Gothenburg, Sweden) requires a two‐stage technique. Purpose: The aim of this study is to compare the outcome of fixed partial bridges in the maxilla supported by both ITI and Brånemark implants in a split‐mouth design. Materials and Methods: Twenty‐eight patients with a residual anterior dentition in the maxilla were included in this split‐mouth study. The Brånemark implants were used on one side and the ITI implants on the other side of the residual dentition according to a randomization procedure. A blocking size of four was used, giving equal probability of placing ITI or Brånemark implants in the right or left side of the jaw. The surgical and prosthetic procedures followed the guidelines given by the manufacturers. The prosthetic treatment with the two‐implant systems was performed at the same time, and for that reason the healing period was 6 months for both systems. The observation period for all patients was 1 year after loading. Results: Two Brånemark implants (in one patient) were lost before loading, and one ITI implant was lost 1 year after loading. There was no significant difference in survival rate. Radiographie examination of the bone level was performed at the time of delivery of the bridge and after 1 year. The mean marginal bone level at baseline was situated 1.9 mm from the reference point for the Brånemark implants and 1.5 mm for the ITI implants. With regard to the insertion depth used, these bone levels indicate that bone loss had taken place before baseline. However, between baseline and the 1‐year examination, there was no significant change of the marginal bone (0.2 ± 0.08 mm at the Brånemark implants and 0.1 ± 0.11 mm at the ITI implants). The difference between results with the two implants was not statistically significant. Crater‐form bone destructions were seen at some ITI implants, indicating periimplantitis. However, at only two implants were there clinical signs of periimplantitis. Conclusions: No significant difference in survival rate or in marginal bone change could be demonstrated between the two systems. At some ITI implants (18%), crater‐form bone loss was observed.     

Marginal Bone Level Changes and Prosthetic Maintenance of Mandibular Overdentures Supported by 2 Implants: A 5‐Year Randomized Clinical Trial

Background: Documentation of early loading of mandibular overdentures supported by different implant systems is scarce. Purpose: This study aimed to compare the biologic and prosthetic outcome of mandibular overdentures supported by unsplinted early‐loaded one‐ and two‐stage oral implants after 5 years of function. Materials and Methods: Twenty‐eight consecutive patients were screened following an inclusion and exclusion criteria, and randomly allocated to treatment groups. Ball‐retained mandibular overdentures were fabricated on two unsplinted Straumann® (Institut Straumann AG, Basel, Switzerland) and Brånemark® (Nobel Biocare AB, Göteborg, Sweden) dental implants and subjected to an early‐loading protocol. During the 5‐year period, prosthetic complications were recorded. At 5‐years of function, plaque, peri‐implant inflammation, bleeding, and calculus index scores were recorded, and standard periapical radiographs were obtained from each implant for measurement of marginal bone loss. Results: All implants survived during the observation period. The peri‐implant inflammation, bleeding, and calculus index scores around Straumann and Brånemark implants were similar (p > .05). The marginal bone loss around Brånemark implants (1.21 ± 0.1) was higher than Straumann implants (0.73 ± 0.06) at 5 years of function (p = .002). Kaplan–Meier tests revealed that 1‐ and 5‐year survival of overdentures on Straumann and Brånemark implants were similar (p = .85). Wear of the ball abutment in the Brånemark group was higher than in the Straumann group (p < .05). Complications regarding the retainer and the need for occlusal adjustments were higher in the Straumann group (p < .05). Chi‐square test revealed that the frequency of retightening of the retainer was higher in the Straumann group than in the Brånemark group (p < .05). Conclusions: Mandibular overdentures supported by unsplinted early‐loaded Straumann and Brånemark implants lead to similar peri‐implant soft tissue and prosthetic outcomes, although higher marginal bone loss could be observed around Brånemark implants after 5 years.     

Brånemark and ITI dental implants in the human bone-grafted maxilla: a comparative evaluation

Abstract: The development of new characteristics concerning implant surface makes it interesting to clinically compare different implant systems in the bone‐grafted maxilla. The aim of this evaluation was to compare clinical data of a two‐staged procedure on the augmented extremely atrophic maxilla using either Brånemark‐ or ITI‐fixures. In 25 patients (18 females, seven males) the severely atrophied maxilla was reconstructed with autogenous iliac or mandibular bone and either Brånemark or ITI implants. Seventy‐eight Brånemark implants and 80 SLA‐ITI implants were inserted in the augmented bone and the patients were followed between 20 and 67 months post implantation. The bone graft was transplanted to add bony volume in the maxillary sinus, the anterior floor of the nose and/or the alveolar ridge. After a healing period of 4½ months, dental implants were inserted and left for healing for 8 months. Twelve consecutive patients received machine‐surfaced Brånemark fixtures and 13 consecutive patients received SLA‐ITI fixtures. Gradual loading was applied after healing abutment application. After 6 months the permanent prosthetic reconstruction was provided to the patient, either as a fixed or removable bridge. Comparison in survival rate was performed: 15 machined Brånemark fixtures were lost, resulting in an overall survival rate of 81%. Two ITI fixtures were lost, resulting in an overall survival rate of 98%. The results of this evaluation show that sandblasted large grit acid etched surface‐treated ITI implants has a significant higher survival rate than machine‐surfaced Brånemark implants in autogenous grafted maxillary bone.     

Is there a lower threshold value of bone density for early loading protocols of dental implants?

This clinical study aimed to determine the bone density in dental implant recipient sites using computerized tomography (CT) and to establish a lower threshold value of bone density for early loading protocols. The study group was composed of 100 early loaded implants in 42 patients. A total of four groups were established according to the loading time and implant sites. The bone density of each recipient site for implant placement was determined using CT. The maximum insertion torque values were recorded with torque controlling machine. Implant stability measurements were performed with resonance frequency analyser. The bone density values varied from 528 to 1231 HU. It was found that mean bone density, insertion torque and resonance frequency analysis values were 887 +/- 180 HU, 41.2 +/- 6 Ncm, and 73.7 +/- 4 ISQ, respectively. Strong correlations were found between these three parameters. CT may be a useful tool for assessing the bone density of recipient areas before implant placement, and the early loading of dental implants may be possible in the implant sites where bone density is over 528 HU.     

Clinical and radiological results of patients treated with two loading protocols for mandibular overdentures on Brånemark implants

Objective: The aim of this study was to evaluate clinical and radiological outcomes of the unsplinted implants supporting mandibular overdenture when applying conventional or early loading protocols. Material and Methods: Twenty‐six edentulous patients were treated with two unsplinted Brånemark System implants supporting mandibular overdenture. There was a test group, in which the overdenture was connected 1 week after surgery, and a control group, in which the overdenture was connected 3 months after surgery. Peri‐implant paremeters were recorded 1, 6, and 12 months after surgery. Clinical stability measurements were performed at surgery, and after 3, 6, and 12 months. Marginal bone levels were evaluated at implant surgery, after 6, and after 12 months. Results: No implant from either group was lost. Clinical peri‐implant parameters, clinical stability measurements, and marginal bone resorptions showed no statistically significant differences between two groups during 12 months. Conclusion: The results of this study suggest that one‐week of early loading protocol of two Brånemark implants supporting mandibular overdenture does not compromise implant stability, marginal bone loss, and peri‐implant soft‐tissue health.     

Adapted preparation technique for screw-type implants: explorative in vitro pilot study in a porcine bone model

Objective: The aim of this study was to quantify the effect of adapted preparation on the insertion torque of self‐tapping implants in cancellous bone. In adapted preparation, bone condensation – and thus, insertion torque – is controlled by changing the diameter of the drilling. Material and methods: After preparation of cancellous porcine vertebral bone with drills of 2.85, 3, 3.15 or 3.35 mm final diameters, Brånemark sytem^® Mk III implants (3.75 × 11.5 mm) were inserted in 141 sites. During implantation, the insertion torque was recorded. Prior to implant insertion, bone mineralization (bone mineral density (BMD)) was measured with dental quantative computed tomography. The BMD values measured at the implant position were correlated with insertion torque for varying bone condensation. Results: Based on the average torque recorded during implant insertion into the pre‐drilled canals with a diameter of 3 mm, torque increased by approximately 17% on reducing the diameter of the drill by 5% (to 2.85 mm). On increasing the diameter of the osteotomy to 3.15 mm (5%) or 3.35 mm (12%), torque values decreased by approximately 21% and 50%, respectively. Conclusion: The results demonstrate a correlation between primary stability (average insertion torque) and the diameter of the implant bed on using a screw‐shaped implant. Thus, using an individualized bone mineralization‐dependent drilling technique, optimized torque values could be achieved in all tested bone qualities with BMDs ranging from 330 to 500 mg/cm³. The results indicate that using a bone‐dependent drilling technique, higher torque values can also be achieved in poor bone using an individualized drilling resulting in higher bone condensation. As immediate function is dependent on primary stability (high insertion torque), this indicates that primary stability can be increased using a modified drilling technique in lesser mineralized bone.     

A descriptive study on retrieved non-threaded and threaded implant designs

Objectives: In the light microscope compare the amount of bone saucerization for non‐threaded cylindrical and threaded implant designs in retrieved samples from patients. Material and method: Consecutively received retrieved oral implants from 117 patients, whereof 85 non‐threaded cylindrical and 85 Brånemark implants, have been included in the study. For 75 non‐threaded cylindrical and 46 Brånemark implants was the entire implant length available for calculation. Undecalcified ground sections were investigated in the light microscope with calculation of percentage of implant length coronal to the first bone–implant contact and percentage of bone to implant contact. Results: Mean value for implant length coronal to first bone–implant contact was 65%, standard error of the mean (SEM) 3 (range 0–100%), for non‐threaded cylindrical implants and 43%, SEM 6 (range 0–100%) for Brånemark implants. Mean values of bone contact along the entire implant length was 23%, SEM 2 (range 0–65%), for the non‐threaded cylindrical implants and 33%, SEM 5 (range 0–93%) for the Brånemark implants. Conclusion: Within the limitations of this retrospective, retrieval study non‐threaded cylindrical implants demonstrated a greater bone saucerization when evaluated in the light microscope.     

One-year prospective three-center study comparing the outcome of a "soft bone implant" (prototype Mk IV) and the standard Brånemark implant

Background: Oral implant treatment ad modum Brånemark has been used for decades in the rehabilitation of edentate and partially dentate patients. Posterior jaw regions frequently exhibit bone of poor texture, and it is often difficult to obtain primary stability. Thus, it may prove beneficial to deviate from the original protocol and to use implants with a modified design, for example, with a slightly tapered geometry. Purpose: The purpose of the investigation was to compare the early behavior of a modified (prototype Mk IV, Branemark System, Nobel Biocare AB, Gothenburg, Sweden; test) implant with that of the standard Brånemark implant (control) in regions of mainly type 4 bone. Materials and Methods: Three Swedish centers participated, and a total of 44 patients were treated with oral implants for 39 maxillas and 5 mandibles. The study focused on the most distal right and left implant sites (88 implants), which were randomized to receive either a test or a control implant. Various parameters were recorded, such as registered insertion torque (OsseoCare, Nobel Biocare AB), wobbling during insertion, primary and secondary stability (as measured with resonance frequency), and marginal bone loss. The implants were followed up for 1 year. Results.: The test implant more frequently required a higher insertion torque and showed a significantly higher primary stability than the control implant. This difference in stability leveled out over time, and test and control implants exhibited similar secondary stability at abutment operation and at the 1‐year visit. Wobbling during insertion was rarely recorded for either of the implant designs. The 1‐year cumulative success rate was 93.1% for test implants and 88.4% for control implants. Conclusions: The modified implant design resulted in an increased primary stability, which may be important when placing implants in jaw regions of type 4 bone. However, independent of the achieved primary stability, successful implants tended to approach similar secondary stability in the two designs tested.     

Biomechanical aspects of primary implant stability: a human cadaver study

Background: The quality of bone is an important factor in the successful implant treatment, and it is evident that higher implant failure is more likely in poor quality of bone. The primary stability of oral implants related to resistance to micromotion during healing is influenced by bone quality, surgical technique, and implant design.
Purposes: The aims of this biomechanical study were to explore the effect of bone quality on initial intraosseous stability of implants, and to determine the correlations between the bone quality and implant stability parameters.
Materials and Methods: Twenty-four implants (Neoss Ltd., Mölnlycke, Sweden) were placed into anterior and posterior regions of three human cadaver mandibles. The bone densities of implant recipient sites were preoperatively determined using computerized tomography (CT) in Hounsfield unit (HU). The maximum insertion torque values were recorded, and primary implant stability measurements were noninvasively performed by means of resonance frequency analysis (RFA).
Results: The bone density values ranged from −267 HU to 553 HU. It was found that mean bone density, insertion torque, and RFA values were 113 ± 270 HU, 41.9 ± 5 Ncm, and 70 ± 7 implant stability quotient (ISQ), respectively. Statistically significant correlations were found between bone density and insertion torque values ( r  = 0.690, p  < .001); bone density and ISQ values ( r  = 0.557, p  < .05); and insertion torque and ISQ values ( r  = 0.853, p  < .001).
Conclusion: CT is a useful tool to assess bone quantity and quality in implant recipient sites, and bone density has a prevailing effect on implant stability at placement.     

Two alternative surgical techniques for enhancing primary implant stability in the posterior maxilla: a clinical study including bone density, insertion torque, and resonance frequency analysis data

Background: The primary stability of dental implants associated with resistance to micromotion during healing is affected by surgical technique and implant design, which are important especially in the soft bone, where implant failures are more likely. Purposes: This study was designed to compare the parameters associated with implant insertion using two different methods of enhancing implant primary stability and to identify any relationship between these parameters at implant insertion. Materials and Methods: A total of 60 implants were placed in the maxillary posterior regions of 22 patients. The bone densities at the implant sites were recorded using a computerized tomography machine in Hounsfield unit (HU). The maximum insertion torque data were recorded with the Osseocare™ (Nobel Biocare AB, Göteborg, Sweden) equipment, while resonance frequency analysis (RFA) measurements were taken using an Osstell™ (Integration Diagnostics AB, Göteborg, Sweden) machine at implant surgery. Comparisons including HU, Ncm, and implant stability quotient were made between two control groups (C1 and C2), and corresponding four test groups (T1–T4) using thinner drills to enhance primary implant stability. Results: Two implants were lost, meaning an overall implant survival rate of 96.6% after 3 ± 1 years. When compared to control groups, significantly higher mean maximum insertion torque and RFA values were found for corresponding test groups. In addition, strong correlations were observed between the bone density and insertion torque, and implant stability values at implant placement. Conclusion: The results of this study suggest that using thinner drills for implant placement in the maxillary posterior region where bone quality is poor may improve the primary implant stability, which helps clinicians to obtain higher implant survival rates.     

Effects of Implant Design and Surface on Bone Regeneration and Implant Stability: An Experimental Study in the Dog Mandible

Background: Previous experimental studies have shown a higher degree of bone‐implant contact for surface‐enlarged implants compared with machined implants. Yet, there is insufficient evidence that such implants show higher stability and an increased survival rate. Purpose: The purpose of this investigation was to study the integration and stability of grit‐blasted implants with retention elements on the implant neck, with and without marginal bone defects, compared with machined implants without retention elements. Materials and Methods: After tooth extraction of the mandibular premolars in six dogs, two grit‐blasted, partly microthreaded Astra Tech implants and one standard Branemark implant were bilaterally placed in each dog. On one side, 3 ± 3 mm large buccal defects were created, to expose three to four implant threads. The contralateral side served as control, and no defects were made. The animals were sacrificed after 4 months of healing. Implant stability was measured using resonance frequency analysis at implant installation and after 4 months of healing. Histologic and histomorpho‐metric evaluation was made after 4 months of healing. Results: Resonance frequency analysis indicated that all implants in the test and control groups were osseointegrated after 4 months, with a tendency toward higher implant stability for the Astra Tech implants. There was a statistically significant higher increase in resonance frequency for the Astra test implants compared with their corresponding controls. Histology and histomorphometry showed well‐integrated implants with varying degrees of bone repair at the defect sites. The greater bone‐implant contact for the Astra implants was statistically significant. No significant difference between the implants in amount of bone filling the threads was recorded. Conclusions: The Astra Tech implants tested showed a higher degree of bone—implant contact and higher level of bone regenerated at defect sites compared with the Brånemark implants. Resonance frequency analysis demonstrated a significantly higher increase in the Astra test implants compared with their control groups than did the Brånemark test implants versus their controls.     

Immediate Occlusal Loading of Single Lower Molars Using Brånemark System® Wide Platform TiUnite™ Implants: A 5‐Year Follow‐Up Report of a Prospective Clinical Multicenter Study

Introduction: Although not essential, molars hold their importance in terms of functional jaw stability, antagonist opposition, and support of facial height. Therefore, implant therapy is an attractive concept in molar areas. However, especially in the posterior mandible, the conventional two‐stage surgical approach to implant therapy was reported to cause higher bone loss and/or higher implant failures with machined implants because of the peculiar anatomic and physiologic conditions of this area. As the TiUnite? (Nobel Biocare AB, Göteborg, Sweden) surface results in faster bone healing than with machined‐surface implants, it was hypothesized that this surface would also improve the performance of wide implants in posterior mandibles. Based on these assumptions, a protocol for immediately loaded implants for single molar replacement was developed. Purpose: This paper aimed to report on the clinical and radiological performance of Brånemark System® TiUnite Wide Platform implants supporting single molars in the lower jaw, loaded immediately and followed for up to 5 years, and to assess if the benefit delivered by oxidized surfaces in the short run is also present after 5 years. Materials and Methods: The study includes 33 consecutive patients treated between March 2001 and September 2003 and monitored until September 2008 in two private dental offices. A total of 40 Brånemark System TiUnite Wide Platform MK III implants were placed. All implants were provided with provisional crowns in full centric occlusion at the time of surgery. Patients were clinically and radiologically followed up for up to 5 years. Results: Two implant failed so that the cumulative success rate at 5 years was 95.0%. The mean marginal bone remodeling (n = 38) expressed as mesial plus distal value averages was ?1.17 mm (SD ± 0.90) at the 5‐year time point. Conclusion: Although limited by the number of patients treated in accordance with the protocol described, 5‐year results encourage the use of immediately loaded single lower molars supported by Brånemark System Wide Platform TiUnite implants and further document the clinical advantages of titanium oxidized surfaces.     

A three-year follow-up report of a comparative study of ITI Dental Implants and Brånemark System implants in the treatment of the partially edentulous maxilla

Background: Many longitudinal studies of different implant systems have been published but few controlled randomized investigations have been reported. A 1‐year report of a comparative study of ITI Dental Implant System® implants (Straumann AG, Waldenburg, Switzerland) and Brånemark System® implants (Nobel Biocare AB, Gothenburg, Sweden) has been published by the present authors. This paper is a 3‐year follow‐up of that randomized study. Purpose: The aim of the study was to compare the outcome of fixed partial prostheses supported by ITI or Branemark implants. The outcome was evaluated primarily in terms of survival rates and changes in marginal bone level. Material and Methods: The study group comprised 28 patients with anterior residual dentition in the maxilla. The patients were provided with two to four implants on each side of the dentition and were randomly allocated to Brånemark implants or ITI implants; 77 ITI implants and 73 Brånemark implants were inserted. After 6 months abutment connections were made to both ITI and Brånemark implants. All patients were provided with fked partial prostheses of gold‐ceramic. The patients were followed up annually with clinical and radiographic examinations for 3 years. Results: Two Brånemark implants and two ITI implants were lost. The Brånemark implants were lost before loading whereas the ITI implants were lost because of periimplantitis. The survival rate for both groups was 97.3%. The mean marginal bone level of the Brånemark implants was situated 1.8 mm from the reference point at both the baseline and the 3‐year examinations. The corresponding values for the ITI implants were 1.4 mm at baseline and 1.3 mm after 3 years. There was no significant difference between the implant systems with regard to bone level or bone level change. A steady state of the marginal bone level was calculated to have been reached after 3 years for 95.5% of the Brånemark implants and 87.1% of the ITI implants. Periimplantitis (infection including pus and bone loss) was observed with seven ITI implants but with none of the Brånemark implants. This difference was statistically significant. Conclusions: No statistically significant differences were found between the implants studied, except for the frequency of periimplantitis, which was higher for the ITI implants. The survival rates were high, and the marginal bone loss was small for both systems.